Linear ball screw-type actuators are used in many applications to transmit linear motion in performing such operations as opening and closing, raising and lowering, pushing and pulling, advancing and retracting, and positioning various devices. In these devices a screw is typically supported within a relatively telescoping inner and outer tube for rotation by a motor and gear box assembly. A ball nut is mounted on the screw and coupled to the slidable inner tube, converting the rotary motion of the motor and screw to linear motion of the inner tube. The inner tube carries a clevis or other connector at its free end which is coupled to the device to be actuated.
Generally, stop washers or pins are provided on the screw at its opposite ends to halt the travel of the ball nut along the screw, thereby establishing fully extended and retracted inner tube stroke limits. The sudden stoppage of the ball nut as it impacts such stops imparts a jolting shock force to the actuator parts, which can be considerable, particularly when the actuator is under heavy load.